Pre-treatment of feed to non-stirred surface bioreactor

Abstract

The invention relates to a process for the pre-treatment of feed to a non-stirred surface heap leach bioreactor by applying in sequence first and second pre-treatment solutions to a feed to a non-stirred surface heap leach bioreactor, in which the first solution has an iron content greater than 5 g/l and pH below 2, and the second solution contains a substantially higher microbial population. The invention further relates to methods of adapting a microbial population for use in a non-stirred surface heap leach bioreactor.

1 . A process for the pre-treatment of a feed to a non-stirred surface heap leach bioreactor which includes the step of applying in sequence first and second pretreatment solutions to a feed to a non-stirred surface heap leach bioreactor, in which the first solution has an iron content greater than 5 g/l and pH below 2, and the second solution contains a substantially higher microbial population. 
   
   
       2 . The process as claimed in  claim 1  in which the microbial population of the second solution is selectively adapted relative to a heap PLS solution. 
   
   
       3 . The process as claimed in  claim 1  in which includes adding additional sulphuric acid concurrently with the iron rich first solution. 
   
   
       4 . The process as claimed in  claim 1  in which the second solution comprises a solution from a dewatering step of oxidised product from the non-stirred surface bioreactor. 
   
   
       5 . The process as claimed in  claim 1  in which the iron rich first solution comprises a re-circulating irrigation solution from a non-stirred surface bioreactor process. 
   
   
       6 . The process as claimed in  claim 2  in which the microbial population of the second solution has been enriched and adapted in an inoculum generator which has been charged with concentrate, sulphur or other material to selectively increase the population of specific microbes in the solution. 
   
   
       7 . The process as claimed in  claim 2  in which microbial population of the second solution contains microbes from an inoculum generator of which the temperature is operated in a predeterminable temperature range to increase the population of specific microbes in the solution. 
   
   
       8 . The process as claimed of  claim 2  in which the solution with the adapted microbial population content contains microbes from an inoculum generator which is fed with concentrate to select microbes most suitable for specific toxic compounds contained in the concentrate. 
   
   
       9 . The process as claimed in  claim 2  in which the solution with the adapted microbial population content contains microbes from an inoculum generator which is fed with a sulphur species to select microbes most suitable for sulphur oxidation. 
   
   
       10 . The process as claimed in  claim 1  in which at least part of the solid phase is separated from the liquid phase after pre-treatment, either prior to treatment with another solution or prior to coating and stacking onto a non-stirred surface bioreactor. 
   
   
       11 . A method of adapting a microbial population for use in a non-stirred surface heap leach bioreactor which includes a microbe selection step in which a solution which contains the microbes is passed through an inoculum generator which is fed with concentrate to select microbes most adapted for specific toxic compounds contained in the concentrate in the non-stirred surface heap leach bioreactor. 
   
   
       12 . A method of adapting a microbial population for use in a non-stirred surface heap leach bioreactor which includes a microbe selection step in which a solution which contains the microbes is passed through an inoculum generator which is fed with a sulphur species to select microbes most suitable for sulphur oxidation in the nonstirred surface heap leach bioreactor. 
   
   
       13 . A method of adapting a microbial population for use in a non-stirred surface heap leach bioreactor which includes a microbe selection step in which an inoculums generator is operated in a specific temperature range to selectively favour a specific microbe most suitable for the temperature operating regime used in the bioreactor in the non-stirred surface heap leach bioreactor.